This invention relates to the mixing of a plurality of electronically controlled light sources which are filtered to produce specific colours and then mixed to make any one of a range of colours including, with appropriate filtering, any colour in the visual spectrum.
Systems for mixing red, green and blue coloured light to produce other colours has long been used to produce colour television pictures. However, in the area of direct lighting the larger the light sources and high powers involved have made it difficult to produce beams of light with homogenous colour. This difficulty arises because of the relatively large size of light sources and the fact that a compromise has to be made between effective colour mixing and efficient beams of light. Colour mixing can be best achieved by diffusing the light whilst efficient beams of light are produced by focusing the light.
A preferred embodiment of the present invention overcomes these problems by creating a wide angle mixing beam in one plane of illumination whilst maintaining a narrow beam in a substantially perpendicular plane. Using such a system makes it possible to illuminate a surface with uniformly colored light of any colour in the spectrum using apparatus containing only three suitably filtered light sources.
A further preferred embodiment of the invention uses semi specular or linear prismatic reflectors combined with small viewing shields to minimize the colour mixing zone and obscure it from view. This allows lighting units embodying the invention to be mounted within low height ceiling voids thus greatly enhancing the number of applications to which they can be put.
In a further preferred embodiment the surface being illuminated has its base inclined towards the viewer.
Preferably, a single action user interface is incorporated which may be a rotary knob or a slider with a purpose made colour scale that defines a set number of colours or change cycles to enable the user to turn the knob or slide the slider to a given colour and that colour will appear.